NBC Universal has launched an online digital advertising network that links 21 of its digital properties, allowing advertisers to reach an unduplicated audience of nearly 60 million unique users each month.

The Universal Audience Platform will sell inventory by targeting specific audiences and not by specific websites.

The platform will use data providers such as Nielsen, Quantcast and BlueKai to offer demographic composition, behavorial patterns, geographic location and purchase intenders. That data will be supplemented with internal NBCU- and client-provided data to help advertisers find the audience they are looking for.

The system will include a capability to tap into major holding-company trading desks such as Omnicom Trading Desk, Adnetik, Cadreon and VivaKi. These in-house companies will provide clients with preferred access to UAP inventory in real-time bidding environments via private exchanges.

NBCU will maintain full control over its inventory during the purchase process.

"Ad networks and portals are a nearly $5 billion marketplace, where third-party ad networks capture a disproportionate share," Peter Naylor, executive VP of digital sales for NBCU, said in a statement. "The UAP allows NBCU to be a key player in this market with a portfolio of leading digital properties. By dialing down third-party ad networks, we're able to take greater control over our digital inventory and provide the marketplace with a new buying opportunity directly from a trusted and premium content source."

The UAP network is making inventory through this system available from all of its entertainment sites, including nbc.com, bravotv.com, oxygen.com, syfy.com and usanetwork.com, as well as from accesshollywood.com, ivillage.com, mun2.com, nbcsports.com, the 10 NBC local media websites, telemundo.com and Universal Home Entertainment.